Set default refspec value as NULL for dependency repos

TF-M dependency versions can be automatically parsed by CI scriptsg from
CMake system now. So keep default refspec value as NULL to use the TF-M
specified dependency version by default.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: I91c4ed7f5a4effb154054f8aeb43f6dccf0ecd9b
diff --git a/tf-m-code-coverage.yaml b/tf-m-code-coverage.yaml
index 8fbab96..252d4c4 100644
--- a/tf-m-code-coverage.yaml
+++ b/tf-m-code-coverage.yaml
@@ -58,7 +58,7 @@
             No need to change.
       - string:
           name: 'MBEDTLS_VERSION'
-          default: 'mbedtls-3.4.0'
+          default: ''
           description: |
             Specify which MBEDTLS version to use
             refs/heads/<branch_name> : Pick up latest HEAD on branch
@@ -72,7 +72,7 @@
           default: 'https://github.com/laurencelundblade/QCBOR.git'
       - string:
           name: 'QCBOR_VERSION'
-          default: '92d3f89030baff4af7be8396c563e6c8ef263622'
+          default: ''
           description: |
             Specify which QCBOR version to use
             refs/heads/<branch_name> : Pick up latest HEAD on branch
@@ -99,7 +99,7 @@
           description: "Name of Jenkins credential for authentication with LAVA."
       - string:
           name: 'MCUBOOT_REFSPEC'
-          default: 'v1.10.0'
+          default: ''
           description: |
             Specify which MCUboot version to use
             refs/heads/<branch_name> : Pick up latest HEAD on branch
@@ -113,7 +113,7 @@
           default: 'https://git.trustedfirmware.org/TF-M/tf-m-tests.git'
       - string:
           name: 'TFM_TESTS_REFSPEC'
-          default: 'refs/heads/master'
+          default: ''
           description: |
             Specify which tf-m-tests version to use
             refs/heads/<branch_name> : Pick up latest HEAD on branch
@@ -124,7 +124,7 @@
           default: 'https://git.trustedfirmware.org/mirror/psa-arch-tests.git'
       - string:
           name: 'PSA_ARCH_TESTS_VERSION'
-          default: '5c5792080f0975775bbdddcd9722da446dce550b'
+          default: ''
           description: |
             Specify which psa-arch-tests version to use
             refs/heads/<branch_name> : Pick up latest HEAD on branch